Industrial light fixtures including a tubular arm, such as an arm made of one or more square channel elements, with one end of the arm attached on a suitable mounting bracket, an electrical lamp at the other end of the arm, and wiring enclosed within the tubular arm and leading to the lamp must be connected to an electrical power supply line when they are installed in the desired area. The typical prior art system for connecting the power supply line to the internal lamp wiring of the light fixture has been to attach a junction box to an external surface of the arm and make the connection between the power supply line and the internal lamp wiring in the junction box.